View Full Version : Lens Distotion node in Nuke

03 March 2010, 10:10 PM

I'm having a problem with this node in Nuke. I'm currently working on a 2k film scan and there is a lot of CG integration. So we've used data from PFtrack to undistort clean plate in Nuke so we can match the CG elements. Now, in final comp we will not undistort original plate, CG will be distorted, however I've noticed that this node is not so good with resempling the image, there are a lot of grid like artifacts. The grain is really "destroyed", in some areas it's blurred, in others is sharp, and these blurred/sharped areas are formed in a grid like pattern, most noticeable in blue channel. It's near impossible to match the grain, but even if the grain is added on CG element distorted with this node (since the original plate will not be processed) this artifact indicate that this node is clearly destroying the image. Node it self does not have any options for filtering or sampling and I really need this to be done in Nuke. Does anyone have any idea how to solve this?

03 March 2010, 02:07 PM
apply the grain after the distortion?

03 March 2010, 02:43 PM
These artifacts that are visible on the grain after distortion are just an indicator that the resampling in this node is not working well... to say the least. Grain after distortion on CG element will "mask" all of the flaws but what I need is to get a nice resampling . I can only imagine what happens when CG render of particles is processed with this undistortion node...

03 March 2010, 01:45 AM
Just a random whacky idea, but you could comp with undistorted plates and cg, render out the images, and then bring them back in and try a lens distort on the image sequence.

OR you could try applying the distortion in some other compositing app to the undistorted image sequence, maybe even try a photoshop batch process. You could also try a degrain on the plate and then apply the grain node to the overall comp, but I dont know how well that will work out.

03 March 2010, 05:16 PM
Have you tried using STMap to re-apply your distortion?

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03 March 2010, 05:16 PM
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